This invention relates to architectural rail systems used to support bullet-resistant panels within buildings, e.g. door panels, window panels, storefront panels, or security barrier panels (in banks, drug stores, cashiers, windows, etc.). The panels can be transparent acrylic panels having the ability to resist penetration by small arms fire. The associated rail systems can be hollow aluminum extrusions for securing the panels to the individual rails. In the case of barrier walls and store fronts, the rails will serve as supporting devices for the panels.
Acrylic panels and other laminated transparent sheet assemblies have the ability to resist penetration or destruction by small arms fire. However, the associated aluminum support rails do not have similar abilities. The present invention contemplates the use of internal ballistic steel panels (strips) within the aluminum rails to reinforce the rails against the passage of ballistic projectiles transversely through the rails.
In carrying out the invention, conventional aluminum rails are modified by the addition of longitudinal track-forming ribs within the hollow interior of the rails. Flat elongated strips of ballistic material (e.g. steel) are slidably moved into and along the tracks to occupy fixed positions within the rails. Each ballistic strip extends the full length of the associated rail.
Each aluminum rail in the system is preferably formed with at least two longitudinal internal tracks. A separate ballistic panel (strip) is inserted into each track. In some cases, it may be necessary or desirable (for cost reasons) to use only one of the tracks, with some reduction in the ballistic protection. One of the tracks is located at or near the front longitudinal wall of the rail. The other track is located at or near the rear wall of the rail. With such an arrangement, the two ballistic panels (strips) are spaced along the path of the projectile. When the rail is subjected to ballistic attack, the frontmost ballistic panel bends or deflects under the force of the projectile, thereby absorbing most or all of the kinetic energy possessed by the projectile. The spacing of the ballistic panels forms an expansion zone that accommodates the rearwardly bulged section of the frontmost panel. The second (rear) ballistic panel acts as a backup interception device to capture any low energy fragments or particles that might be shed from the projectile or the deflected portion of the front ballistic panel.
The "spaced panel" system of this invention avoids the punchthrough action that can sometimes occur when ballistic panels are placed flat against one another without any spacing along the direction of projectile motion. In such cases, the front panel is reinforced by the rear panel so that the front panel cannot deflect to effectively absorb projectile energy. The projectile tends to punch through the panels so that fragments are sprayed into the zone behind the protective panels.
The present invention is perceived as a relatively low cost method for providing aluminum architectural rails with effective ballistic protection features. Multiple tracks are integrally formed in the rails, such that ballistic panels can be selectively inserted into one or all of the tracks to provide different levels of protection.